Method of making a switch with molded bearing

ABSTRACT

THIS APPLICATION DISCLOSES A SWITCH CONSTRUCTION MADE BY MOLDING A RELATIVELY HIGH TEMPERATURE RESISTANT THERMOSETTING MATERIAL INTO A SWITCH BASE WITH A SHAFT OPENING PASSING THROUGH THE BASE, AND FORMING A SHAFT BEARING IN SAID OPENING OF RELATIVELY LOW TEMPERATURE ELASTIC LIMIT THERMOPLASTIC MATERIAL, SAID BEARING BEING FORMED AT A TEMPERATURE OF SAID RELATIVELY LOW TEMPERATURE ELASTIC LIMIT. A SWITCH IS PLACED ON SAID BASE AND A SWITCH SHAFT IS INSERTED IN SAID BEARING AND OPERATIVELY CONNECTED TO SAID SWITCH.

March 16, 1971 w, ADAMS ETAL 3,570,120

METHOD OF MAKING A SWITCH WITH MOLDED BEARING Original Filed May 24,1965 v 2 Sheets-Sheet.1

FIG?! H672 20 Q t-i i I '1' I El INVENTOR) WILLIAM E. ADAMS WERNERR.BAUER aoo FIG-I5 BY JOHN B.$CHUL'IHEIS THEIR ATTORNEYS March 16,- 1971w, ADAMS ETAL 3,570,120

METHOD OF MAKING A SWITCH WITH MOLDED BEARING Original Filed May 24,1965 2 Sheets-Sheet 2 INVENTORf WILLIAM E.ADAMS WERNE RJBAUER BY JOHN B.ULTHEIS THEIR ATTORNEYS United States Patent 3,570,120 METHOD OF MAKINGA SWITCH WITH MOLDED BEARING William E. Adams, Broadview Heights, Ohio,Werner R.

Bauer, Raduor, Pa., and John B. Schultheis, Worthington, Ohio, assignorsto Robertshaw Controls Company, Richmond, Va.

Original application May 24, 1965, Ser. No. 458,223, now Patent No.3,392,253, dated July 9, 1968. Divided and this application Jan. 30,1968, Ser. No. 701,593

Int. Cl. H01h 11/00 U.S. Cl. 29-622 9 Claims ABSTRACT OF THE DISCLOSUREThis application discloses a switch construction made by molding arelatively high temperature resistant thermosetting material into aswitch base with a shaft opening passing through the base, and forming ashaft bearing in said opening of relatively low temperature elasticlimit thermoplastic material, said bearing being formed at a temperatureof said relatively low temperature elastic limit. A switch is placed onsaid base and a switch shaft is inserted in said bearing and operativelyconnected to said switch.

This application is a division of applicants copending application Ser.No. 458,223, filed May 24, 1965 for Thermosetting Switch Support WithThermoplastic Bearing.

This invention relates to a switch with a molded bearing and method ofmaking the same.

One of the features of this invention includes a switch construction andmethod of making the same in which the base of the switch is made of arelatively high temperature resistant and electrically insulatingthermosetting material with the material being permanently set. A switchactuating shaft opening is molded during the thermosetting operation topass through said permanently set base. A shaft bearing is thereafterformed in such shaft opening, the bearing being made of relatively lowtemperature elastic limit thermoplastic material with the bearing beingformed substantially at or in the neighborhood of such relatively lowtemperature of the elastic limit of the thermoplastic material. Thisfeature permits the base to be formed or molded at the relatively hightemperatures required for molding the thermosetting material withoutharming the bearing. Thereafter, the bearing may be formed at saidrelatively low temperature in the neighborhood of the elastic limit ofthe thermoplastic material without harming the previously molded base.

Other features of this invention become apparent from this description,the appended claimed subject matter, and/or the accompanying drawings inwhich:

FIG. 1 is a top plan view of a switch construction according to thisinvention, the parts being shown substantially in actual scale in thepatent application drawings.

FIG. 2 is a left end elevation of the switch construction of FIG. 1.

FIG. 3 is a top plan view of the switch construction of FIG. 1 inenlarged scale and with the cover removed.

FIG. 4 is a view similar to FIG. 3 with the switch parts in actuatedposition.

FIG. 5 is a vertical cross section substantially along the line 55 ofFIG. 3.

FIG. 5A is a view similar to certain parts of FIG. 5 taken adjacent theplane of one of the switch blades.

FIG. 6 is a plan view of the base member shown in FIG. 3 as molded ofthermosetting material and without any additional parts and in reducedscale.

3,570,120 Patented Mar. 16, 1971 FIG. 7 is a side view of FIG. 6 takenfrom line 77 of FIG. 6.

FIG. 8 is a cross section along line 88 of FIG. 6, in slightly enlargedscale.

FIG. 9 is a vertical cross section showing the injection molding processof the shaft bearing in the shaft opening of the switch base, with theshaft bearing being shown in cross section substantially along the line9-9 of FIG. 14.

FIG. 10 shows the apparatus of FIG. 9 at a later stage, with one of themolding dies removed.

FIG. 11 is a plan view of a portion of the base shown in FIG. 6, withthe shaft bearing having been molded therein.

FIG. 12 is a vertical cross section taken along the line 1212 of FIG.11.

FIG. 13 is a vertical cross section taken along the line 1313 of FIG.11.

FIG. 14 is a top plan view of the shaft bearing shown in FIGS. 9 and 10in a slightly reduced scale.

FIG. 15 is a diagrammatic cross section showing another embodiment ofthe invention.

FIG. 16 is a cross section of the preformed shaft bearing to be used inFIG. 15.

Certain words indicating direction, relative position, etc., are used inthis specification and in the claims for the sake of brevity andclearness. However, it is to be understood that such words are used onlyin connection with the direction, relative position, etc., as shown inthe drawings, and that, in actual use, the parts so de scribed may haveentirely different direction, relative position, etc. Examples of suchwords are upper, lower, vertical, horizontal, etc.

A switch, and method of manufacturing such switch are disclosed in thedrawings of this application and in the description thereof.

A switch according to this invention is diagrammatically shown in FIG. 1substantially in actual scale in the application drawings. This switchconstruction is shown in top plan view of FIG. 1, wherein a cover 20,and a base 22 form an insulating casing for the switch constructionwhich may be mounted on the base 22.

The cover 20 and the base 22 may be made of a phenolic moldingthermosetting resin of any suitable type, which is of relatively hightemperature resistance and is electrically insulative. For example, suchbase may be made of the material well known in the trade as Bakelite, orany other suitable similar material.

Such base 22 is shown in FIG. 6, with no other parts attached thereto,the base also being shown in FIG. 7 in side elevation, and in FIG. 8 invertical cross section.

Such base may be rectangular in shape, if desired, and may be generallyfiat in shape, and may be made or molded from such thermal settingmaterial with a shaft opening 24, and with parallel indentations ortroughs 26 on each side of the opening 24.

Other openings and irregularities may be formed on the base 22. Forexample, the openings 28 may be for the purpose of receiving fasteningscrews-that will fasten the cover 20 to the base 22, and both of thesemembers to any support which may be desired. Other openings 30 mayreceive rivets to fasten metal conductors 31A on the base, whichconductors may be placed in the shallow troughs 32. These conductors,which are embedded in the troughs 32 may have terminal extensions 34,FIGS. 1-4.

A switch actuating shaft bearing 36 may be formed of relatively lowtemperature elastic limit thermoplastic material, which may be injectionmolded in the opening 24, and in the adjacent extrusion molds 38 and 40.

The plastic material for the bearing 36 may be any suitablethermoplastic material, which may be injection molded, and may have asufiiciently relatively low temperature elastic limit, and injectionflow temperature, so that the same may be injection molded in thepreviously formed thermoset base 22. For example, such thermoplasticmaterial may be an acetal resin, such as is known in the trade asDelrin, and manufactured by the E. I. du Pont de Nemours Co., Inc., ofWilmington, Del.

The injection molds 38 and 40 may be moved tightly against oppositesides of the previously molded base 22, and over the opening 24. Themold 38 may have a chamber 42, which has a pilot pin 44 passingtherethrough. The chamber 42 is connected by a passageway 46 to a sourceof supply of the thermoplastic material, such source being capable ofproducing the necessary pressure and temperature to injection mold thebearing in the casing 42, opening 22, and lower chamber 48 in the lowermold If desired, the lower mold 40 may have a small lip 50 extendinginto a flange forming circular recess 52, which is adapted to form thelower circular flange 54.

The base 22 which may be molded from a suitable relatively hightemperature resistant and electrically insulating thermosettingmaterial, such as a suitable Bakelite, is capable of resistingtemperatures in the order of 450 F. for sufficiently long periods oftime, for the purpose herein disclosed, without damage. Thethermoplastic material, such as the acetal resin known as Delrin, mayhave an operating injection range of from 380420 P. so that the base 22is not subjected to any destructively long high temperature, since theinjection, once it has been made at a temperature below the safe limitof Bakelite, is cooled as quickly as possible so that it may harden intothe finished shaft bearing without damaging the base 22.

The shaft bearing 36 is flanged against the ends of the opening 24 suchas by producing the upper flange 56, and a lower flange 54, which iscircular in shape.

The upper flange 56 of the shaft bearing may be in the form of a centraltube 58, FIG. 14, which has an inner cylindrical surface 60 and an outercoaxial cylindrical surface 62 and which has two parallel wings 64secured to the outer cylindrical surface 62. If desired, the parallelwings may have downward parallel extensions 66, FIG. 9, which extendinto the base 22 at the indentations or troughs 26, which are shown inFIGS. 6, 9 and 10.

The shaft bearing may have a circular lower flange 54 extending into acircular recess 52 at the lower end of the shaft opening. A cylindricalbearing wall 68 extends below the lower flange 54 with coaxial inner andouter surfaces 70 and 72 respectively.

In the embodiment of FIG. 15, a base 22 may be substantially the same asthe base 22 heretofore described, and may be provided with a shaftopening 24, substantially the same as shaft opening 24 heretoforedescribed.

The base 22 of FIG. 15 may be made of the relatively high temperatureresistant and electrically insulative material heretofore described,such as Bakelite.

A shaft bearing may be preformed of a relatively low temperature elasticlimit thermoplastic material, such as Delrin.

The shaft bearing 80, FIG. 16, may be preformed in the form of a bearingtube 82 having an unflanged bearing end 84 and a flanged bearing end 86,which end 86 has a flange 88.

The tube or shaft bearing 80 may be introduced into the opening 24 withthe unflanged bearing end 84 initially inserted in the first shaftopening end 90, and finally extending out of the second shaft opening 92and with the flanged bearing end 86 adjacent the first shaft opening 90.

The base 22 of FIG. 15 and the tubular bearing 80 may then be heatedtogether substantially to the relatively low temperature elastic limitof the thermoplastic material. Then a second or last formed flange 94may be outwardly cut or flanged or staked by the staking tool 96 after apin 97 has been inserted in the shaft opening 98 A backup mold or tool100 may be placed adjacent the end 86 4 of the preformed bearing 80. Thetool may have a lip 102, to hold the flange 88 firmly in place, whilethe other end of the bearing is being staked by the tool 96. If desired,the flange 94 may befirmly pressed at the end 92 as far down as desiredso that the bearing may be held in place.

If desired, the bearing 80, and the opening 24 of FIG. 15 may be made ofirregular transverse cross section to prevent the shaft bearing 80 fromturning. That is, the outer surface 104, FIG. 16, of the bearing 80 andthe inner surface 106 of the opening 24 may be square, elliptical or thelike, so that the shaft bearing 80 cannot turn after the bearing hasbeen staked in place.

The tools such as the rod 97, and the fixture 100, and the staking tool96 are held in place, until the thermoplastic material has cooled belowthe elastic limit, so that it is maintained in the proper form until ithas properly crystallized. Thereafter, such tools may be removed.

The switch structure that may be mounted on the base 22 may be of anydesired form. For example, it may have a contact carrying blade 104,FIGS. 35A, which carries the movable contact 106, and which is mountedon a bracket 108, which is an upward flange of the conductor 31A, ofFIG. 3. An actuating blade 110 is also mounted on the bracket 108. Theblades 104 and 110, have tongues which engage the snap spring 112, in awell known manner. The snap spring 112 causes the blade 104 to snap thecontacts '106 back and forth to and from the stationary contacts 114 and116. An actuator insulating rod 118 has an opening through which thewire 120 passes. One end of the wire enters the bracket 122, whichbracket 122 is carried by the double-ended lever 124 which is secured tothe actuating shaft .126, which shaft passes through the bearing 36 or80 heretofore described. The other end of the wire 120 is secured topost 128 which may be integral with the base 22, the wire 120 beingwound around a metal pin 130, which supports the upper part of the post128.

The end 132 of the lever 124 engages the wings 64 of the bearing member,and limits the oscillating action of the actuating shaft 126. A suitablerocking member 134 may oscillate the actuating shaft 126 in any suitablemanner. The member :134 may in turn be actuated manually, automatically,or in any other manner desired.

While the form of the invention now preferred has been disclosed asrequired by the statutes, other forms may be used, all coming within thescope of the claims which follow.

What is claimed is:

1. A method comprising:

molding a relatively high temperature resistant and electricallyinsulating thermosetting material into a one-piece switch base with aswitch actuating shaft opening passing through said base and groovemeans adjacent said opening and interrupting one of the opposed faces ofsaid base;

forming a one-piece switch actuating shaft bearing of relatively lowtemperature elastic limit thermoplastic material in said shaft openingwith flange means in said groove means to limit movement of said bearingin one direction relative to said base, said bearing being formed at atemperature of said relatively low temperature elastic limit;

placing a switch on said base;

and inserting a switch actuating shaft through said bearing andoperatively connecting said shaft to said switch.

2. A method according to claim 1 in which said shaft bearing isinjection molded into said shaft opening.

3. A method according to claim 1 in which said shaft bearing is formedin said shaft opening and flanged against the ends of said shaftopening.

4. A method according to claim 3 in Which said shaft bearing isinjection molded in said shaft opening and flanged against the ends ofsaid shaft opening.

'5. A method according to claim 4 in which said shaft bearing ispreformed into the form of a bearing tube of said thermoplastic materialwhich is inserted into said shaft opening and then is heated to saidrelatively low temperature elastic limit and has flanges of saidthermoplastic material secured to the ends of said shaft opening and tosaid bearing.

6. A method according to claim 2 in which said shaft bearing has anupper flange of said thermoplastic material in the form of a centraltube whichhas an inner cylindrical surface and an outer coaxialcylindrical surface and with two parallel wings secured to said outercylindrical Wall.

7. A method according to claim 6 in which said wings have downwardparallel extensions in said base.

8. A method according to claim 7 in which said shaft hearing has acircular lower flange defining said flange means and extending into acircular recess defining said groove means at the lower end of saidshaft opening.

9. A method according to claim 8 in which said shaft hearing has acylindrical wall below said lower flange with coaxial inner and outersurfaces.

References Cited UNITED STATES PATENTS 5/1950 Leahy 264--249 11/ 1956Bowerman 264-269 7/1960 Stahl 264--249 5/1962 Zunker et al 338- 1638/1965 Hulbert 338--163X 5/1968 Jepson et al 29-149.5 10/ 1965 Wallace.

4/1966 Stephan 264-249 3/ 1966 Holbrook 308238X FOREIGN PATENTS Italy.

JOHN F. CAMPBELL, Primary Examiner R. W. CHURCH, Assistant Examiner US.Cl. X.R.

